Staircase based differential privacy with branching mechanism for location privacy preservation in wireless sensor networks

The privacy of an event is a critical aspect of safety in wireless sensor networks. Specially, the location privacy of the reporting sensor nodes is essential to preserving the privacy of the event. Protection the privacy of both the event and the node that observes and reports the corresponding event is critical. In this work, we present a differentially private branching framework for guaranteeing the location privacy of a node and subsequently the event. The proposed framework is based on the premise that an event is normally observed by multiple nodes. This leads to a low sensitivity to transmission by a single source node for the transmissions triggered by an event. If an event is reported by small number of nodes, additional fake traffic is required to be generated. Additionally, dummy sources are required to prevent backtracking. The privacy of an event also imposes the constraint that an adversary must not be able to distinguish between real and fake traffic. Results show that the mechanism initially adds small number of dummy sources which increases the number of source nodes. Later the branching mechanism adds large number of virtual nodes in branches emanating from the routing paths rooted in dummy sources. This increases the number of apparent source nodes substantially thereby ensuring location privacy of the source node.